Skip to Content

Grow Mushrooms in Coffee Grounds: Easy and Sustainable (2023)

This site is supported by our readers. We may earn a commission, at no cost to you, if you purchase through links.

grow mushrooms in coffee groundsAre you ready to take your mushroom cultivation game up a notch? You don’t need expensive equipment or lab-grade materials to grow mushrooms – all you need is coffee grounds!

Growing mushrooms in coffee grounds is an easy and sustainable way to cultivate gourmet Oyster mushrooms. With no need for sterilization, easy sourcing of substrate, plus local food production and a sustainable protein option; there are plenty of reasons why this method should be added to any budding mycologist’s arsenal.

It won’t take long before you’re harvesting your own delicious fungi from the comfort of home.

First, sourcing coffee grounds is easy with the rise in coffee shops and cafes. Simply ask your local coffee shop to set some used grounds aside for you each week. The grounds are often discarded anyway, so most shops are happy to do this. You’ll want coarsely ground coffee for optimal mycelium growth.

Next, you’ll need a growing container. Shallow plastic storage bins work perfectly, as this mushroom variety grows horizontally across the surface.

Now add your substrate. Put down 2-3 inches of moistened coffee grounds in the tub and mix in some dried crushed eggshells.

Inoculate the coffee grounds with Oyster mushroom grain spawn, scattering it evenly over the surface. Then simply put the lid on, keep it somewhere dark and wait as the mycelium colonizes the substrate.

Finally, move the bin somewhere light and airy. Mist it with water 1-2 times a day to maintain humidity.

Key Takeaways

  • Coffee grounds are an easily sourced material from local cafes to grow mushrooms. This allows for a sustainable protein source close to home. Waste products like used coffee grounds can be recycled into gourmet mushrooms. Experimenting with different coffee roast types, such as light, medium, and dark roasts, can influence mushroom growth and flavor.

Benefits of Growing Mushrooms on Coffee Waste

Benefits of Growing Mushrooms on Coffee Waste
Looking for an eco-friendly and nutritious way to grow mushrooms? Coffee grounds provide an excellent medium as they eliminate the need to sterilize the substrate while being abundant, local, and low-cost.

As a bonus, you’ll reduce waste while enjoying homegrown, sustainable protein and learning a new skill.

No Need to Sterilise Substrate

You can skip the step of sterilizing the substrate since the fresh coffee grounds help prevent contamination. The natural acidity and microbial richness of fresh grounds creates an environment ideal for mushroom growth.

By inoculating with mushroom spawn soon after collecting the grounds, you can avoid sterilization while still preventing contaminants from gaining a foothold. This eliminates extra steps and makes the overall process more sustainable and accessible for small-scale fungal cultivation.

Easy to Source Substrate

Collecting fresh coffee grounds daily from local cafés makes sourcing substrate effortless. Simply ask baristas to set aside their discarded grounds. Then inoculate the grounds with your preferred mushroom spawn.

The used coffee provides an ideal nourishing base for oyster, shiitake, lion’s mane and other gourmet mushroom varieties. Monitor conditions such as moisture, humidity and indirect light. Soon you will be harvesting fresh mushrooms using this innovative upcycling method.

Local Food

Consuming homegrown oyster mushrooms from spent coffee grounds cuts your food miles more than riding a bike across the country does. Choosing mushrooms over meat provides sustainable protein close to home. Tap into the local circular economy by collecting grounds from cafes and returning mushrooms to your community.

Urban cultivation means food security and sovereignty in place of reliance on distant industrial agriculture. Growing an edible urban mushroom farm on waste right outside your door allows you to cultivate food locally.

Sustainable Protein

Pursuing sustainable protein through mushroom cultivation conserves resources while giving flavorful results. Creating mushroom spawn from used coffee grounds provides a low-tech, nutritious protein source.

This innovative farming method recycles waste into gourmet mushrooms, reducing environmental impact. The spent coffee substrate also enriches gardens. With simple techniques, you can sustainably harvest abundant edible mushrooms.

Growing oyster mushrooms on recycled grounds is one way to cut environmental impact while producing nutritious food. The leftover substrate from mushroom cultivation can enrich soil in gardens. Sustainable mushroom farming uses waste products like used coffee grounds to grow delicious, earth-friendly crops.

How to Grow Mushrooms in Coffee Grounds

How to Grow Mushrooms in Coffee Grounds
Consider growing mushrooms in used coffee grounds. First, collect fresh grounds from your local coffee shop. Next, mix mushroom spawn and pasteurized straw or sawdust into the grounds. Then, incubate the mixture in a warm, dark place for 2-3 weeks.

Step 1: Collect Fresh Coffee Grounds

You’re sourcing local cafes for unused grounds to recycle. Pursuing mycological innovation? Collect freshly brewed coffee grounds daily.

Step 2: Inoculate With Mushroom Spawn and Straw/Sawdust

After pasteurizing the straw by boiling for over an hour, you’d inoculate it and the coffee grounds with oyster mushroom spawn to kickstart growth.

  1. Sanitize the room and materials.
  2. Mix mushroom spawn into the coffee and straw blend.
  3. Seal the mixture in clear plastic bags.
  4. Poke small holes for air circulation.

Then incubate in a warm, dark area until the mycelium grows, indicating the mixture is ready to fruit with indirect light and moisture.

Step 3: Incubate in a Warm, Dark Place

Once the inoculated coffee grounds are sealed in bags, keep them in a warm, dark place to allow the mycelium to grow undisturbed. The ideal conditions for mushroom growth at this stage are darkness and steady warmth around 75°F.

Periodically check bags to ensure the developing fungal mycelium has adequate moisture and humidity. Avoid disturbing the delicate white mycelium’s progress as it colonizes the substrate during this incubation period, essential for preparing the oyster mushrooms to eventually fruit.

Step 4: Provide Fruiting Conditions

Having incubated the coffee grounds, now move them into indirect light while regularly misting to initiate fruiting.

  • Provide moisture and humidity.
  • Allow for indirect sunlight.
  • Maintain proper ventilation.

The fruiting bodies will soon emerge. Once the caps flatten, the oyster mushrooms can be harvested for a sustainable crop using coffee grounds.

Step 5: Harvest When Caps Flatten

Monitor the basidiocarps closely and harvest them promptly when their caps become planar. After harvesting, rewet the substrate to allow for multiple flushes of mushrooms. The competitive race between the mushrooms makes for an exciting fruiting environment.

Time to Harvest Signs Mushrooms are Ready Harvesting Method
When caps flatten out Caps open fully parallel to stem Twist gently to remove
Just before veil tears Gills exposed, veil intact Cut mushroom at base
Before spores drop Spores visible as dark powder Use knife or scissors

Extend harvest time through the stem base and multiple flushes. Like Paul Stamets says, pay close attention for the optimal mushroom harvest.

Alternative Method: Growing Mushrooms With Coffee Grounds and Cardboard

Alternative Method: Growing Mushrooms With Coffee Grounds and Cardboard
First, cut cardboard to fit your container, then layer it with mushroom spawn and fresh coffee grounds. After incubating it in the dark, move the container to an area with indirect light and high humidity to grow mushrooms, harvesting multiple times before reusing the spent grounds in your garden.

The cardboard and coffee grounds provide a moist, nutritious growing medium for the mushrooms. Make sure the container has drainage holes and does not retain standing water, as mushrooms thrive in damp but not soggy conditions.

Try experimenting with different types of mushrooms and coffee grounds from light roasts to dark roasts to influence flavor. Maintain stable humidity and indirect sunlight for best results. With some patience and the right environment, you can grow several flushes of mushrooms for free using recycled grounds and cardboard destined for the landfill.

Step 1: Prepare Cardboard and Container

First, choose a plastic tub or box that is a few inches deep with a lid. This creates a miniature greenhouse with humidity control. Next, soak corrugated cardboard overnight in water. This softens it for folding.

Lastly, select fresh coffee grounds without mold for optimal mushroom growth. With the preparation complete, it is time to begin layering your mushroom habitat.

Step 2: Layer Mushroom Spawn, Coffee Grounds, and Cardboard

After sanitizing your work area, alternate layers of moistened cardboard, mushroom spawn, and fresh coffee grounds in the container. Carefully pour mushroom spawn over the coffee grounds and cardboard. Check on mycelium growth in a week.

Once the mycelium network is established, move the container to indirect light. Mist and rotate daily until mushroom pins emerge. Harvest young mushrooms gently before the caps flatten. Coffee compost will continue to yield more nutrient-rich fungi.

Step 3: Incubate in a Dark Area

Next, loosely drape a plastic bag over your mushroom kit and incubate it in a dark area for about 2 weeks, checking moisture levels periodically. The mycelium will spread through the coffee grounds during this incubation, forming a thick white mat.

Once pins or primordia emerge after about 3-4 weeks, move the kit to indirect light and maintain humidity to initiate fruiting. Reusing spent coffee grounds reduces waste while growing nutrient-rich mushrooms.

Step 4: Move to a Growing Environment

When the mycelium has fully colonized, it’s time to move the container to an area with ample indirect light and at least 60% humidity for optimal mushroom growth.

Provide indirect sunlight or grow lights on a 12 hour on/off cycle. Mist the container daily and avoid direct water contact. Maintain 60-90% humidity with a humidifier or spray bottle. Harvest mushrooms delicately when caps start to flatten.

A clear plastic tote or bag works well for observing growth during fruiting. With the right conditions, you’ll be rewarded with a bountiful mushroom harvest in as little as a week after introducing light.

Step 5: Harvest Multiple Times

You’ll have several bountiful harvests if you continue misting and providing light. Reuse spent coffee grounds after each harvest to maximize yields. Gently twist or cut mushrooms at the base using sterile tools.

Maintain ideal growing conditions for extended fruiting and multiple flushes. With good technique, you’ll reuse grounds through 3-5 harvests.

Dealing With Contamination and Mold

Dealing With Contamination and Mold
Deal with any contaminants quickly by removing the mold and wiping with diluted hydrogen peroxide.

  1. Inspect daily for any fungal or bacterial growth.
  2. Quarantine affected areas to prevent spreading.
  3. Improve airflow and lower humidity to inhibit mold.

Stay vigilant for signs of contamination. Address any mold, fungi or bacteria right away by surgically removing visible growth. Then wipe down affected surfaces using a dilute hydrogen peroxide solution to sanitize.

Keep your growing areas clean and take preventative measures to limit chances of contamination. Quick action preserves your crops and prevents proliferation. With diligent fungal hygiene and clean cultivation practices, you can sidestep issues and keep your mushroom harvesting on track.


In the blink of an eye, you can turn coffee grounds from your local café into a sustainable, nutrient-rich source of protein with Oyster mushrooms. With the right supplies and a bit of patience, you can easily grow mushrooms from used coffee grounds.

Start by collecting fresh grounds. Inoculate them with Oyster mushroom spawn and pasteurized straw or sawdust.

For another method, prep cardboard and containers. Layer the mushroom spawn, coffee grounds, and cardboard.

To avoid contamination, remove any mold. Use diluted hydrogen peroxide. With some effort and knowledge, you’ll enjoy mushrooms grown from spent coffee grounds.

Avatar for Mutasim Sweileh

Mutasim Sweileh

Mutasim is a published author and software engineer and agriculture expert from the US. To date, he has helped thousands of people make their yards lush and thick.